Battery open circuit voltage

[Jonndeka]

Hi,

I'm investigating SOC-OCV for Li-ion battery for SOC estimation.

I have checked a lot of papers in this matter.

I got a bit confused on the U_ocv calculation part. In general, the definition of open circuit voltage is such that the battery is not connected to any load and has reached a stable state voltage, and at that time we can measure the open circuit voltage of the battery.

But in practice, when the battery is under operation, for example, the electric vehicle is switch on, it is not possible to measure the open circuit voltage. Because the battery is connected to the load (traction motor).

In most papers, we should also have the equations used U_ocv (please see the figure below). Well, when the EV is switch on and the battery is connected to the load, is it correct to get this parameter?

​

I think I had a little trouble understanding this part. Anybody has comments?

I look forward to hearing from your feedback.

 

[eMark]

But in practice, when the battery is under operation, for example, the electric vehicle is switch on, it is not possible to measure the open circuit voltage. Because the battery is connected to the load (traction motor).

I would think even doing that test would be the 1st step when a dealership does a diagnostic test on a used EV automobile.

Anyway considering your latest post (and previous EV battery SOC/SOH posts) you have yet to determine the condition of battery (OCV) in your used EV automobile. Guess that's the conundrum when buying or selling an older used EV auto. Apparently dealerships aren't that helpful in diagnosing (OCV & SOC/SOH) the condition of a used EV auto battery. At least that's the impression i'm left with from all of your (similar) recent post(s).

It might be worth your time to survey local EV dealerships. Determine if there is a diagnostic test they use to determine SOC/SOH (based in part on OCV) before putting a used EV on their used car lot.

Battery Health Before Buying (Nissan Leaf EV) ...

Battery health check before buying

Experts, I can not understand what is causing this difference in numbers? can you help plz Ahr = 57.23 HX = 85.37% (It was around 87 and got lower when fully charged) SOH = 92.16% 12 Bars on DashBoard GIDS = 270 (96.1%) got charged when fully charged (100% on DashBoard) with 20.9 KWH as per...

mynissanleaf.com

Battery Test For Electric Cars ...

Battery Test for Electric Cars | DEKRA

Fast. Independent. Transparent. DEKRA’s quick and precise battery test for used electric cars determines the remaining battery capacity.

www.dekra.com

Are there auto shops that specialize in diagnosing the battery condition of used EV autos ?
Is there a KIS method for self-testing the general condition (SOH) of the battery in a used EV auto ?

 

[Jonndeka]

I would think even doing that test would be the 1st step when a dealership does a diagnostic test on a used EV automobile.

Anyway considering your latest post (and previous EV battery SOC/SOH posts) you have yet to determine the condition of battery (OCV) in your used EV automobile. Guess that's the conundrum when buying or selling an older used EV auto. Apparently dealerships aren't that helpful in diagnosing (OCV & SOC/SOH) the condition of a used EV auto battery. At least that's the impression i'm left with from all of your (similar) recent post(s).

It might be worth your time to survey local EV dealerships. Determine if there is a diagnostic test they use to determine SOC/SOH (based in part on OCV) before putting a used EV on their used car lot.

Battery Health Before Buying (Nissan Leaf EV) ...

Battery health check before buying

Experts, I can not understand what is causing this difference in numbers? can you help plz Ahr = 57.23 HX = 85.37% (It was around 87 and got lower when fully charged) SOH = 92.16% 12 Bars on DashBoard GIDS = 270 (96.1%) got charged when fully charged (100% on DashBoard) with 20.9 KWH as per...

mynissanleaf.com

Battery Test For Electric Cars ...

Battery Test for Electric Cars | DEKRA

Fast. Independent. Transparent. DEKRA’s quick and precise battery test for used electric cars determines the remaining battery capacity.

www.dekra.com

Are there auto shops that specialize in diagnosing the battery condition of used EV autos ?
Is there a KIS method for self-testing the general condition (SOH) of the battery in a used EV auto ?

Thanks for your comment.

well, battery supplier give me helpful information such as OCV-SOC, DCIR, cycle life and so on. And know I'm trying to understand how can I use them for SOC/SOH estimation. That's why I read papers to understand the fundamental of this task.